1. Field of the Invention
This invention relates to an apparatus for opening a flatly folded tube of synthetic resin or the like material and fitting same on a container or the like.
2. Description of the Background Art
Examples of prior art apparatuses of this type are shown in Japanese Patent Application Laid-Open No. 62-122918 and Japanese Patent Publication No. 44-18473, both covering apparatuses developed by the present applicant prior to this application.
These prior art apparatuses are of such arrangement that, as FIG. 7 shows, two horizontally opposed suction belts 2, 2a are spaced so that the distance between them becomes larger toward leading ends of the belts, whereby a flat tube 5 is progressively spread and opened as it is transported by the belts 2, 2a while being held at opposite sides thereof against the belts by suction. Below the space between the pair of belts 2, 2a, as FIG. 7(b) shows, there is provided a holder-carrier device 30 for effecting ascent and descent and horizontal movement of an object 8 such as a container.
According to such arrangement, an object 8 supplied to a position below the opened tube 5 is elevated and inserted into the tube 5, which is then transported forward until the tube 5 is separated from the belts 2, 2a, whereby the tube 5 is fitted over the object 8.
Such arrangement permits easy spreading and opening of flat tubes in the course of transport thereof and, as compared with other known arrangement such that a flat tube is spread and opened by means of a mandrel to a configuration conforming to the shape of the object to be wrapped, the arrangement is advantageous in that the apparatus is relatively simple in construction.
With the aforementioned prior art arrangement, however, one drawback is that since the insertion of each object 8 into an opened tube 5 is carried out through ascent and descent, as well as horizontal movement, of the object 8 by means of the holder-carrier device 30, a very complicated mechanism is required for drive control of the holder-carrier device 30 for such ascent and descent and horizontal movement, which leaves much yet to be improved with respect to the holder-carrier device 30 from the standpoints of ease of manufacture and manufacturing cost economy.
Another drawback is that the track of movement of the object 8 such that the object 8 is moved vertically upward and then moved horizontally does not permit smooth movement and is therefore unsuitable for use where high speed operation is required.
A further drawback is that the arrangement in which the object 8 is moved upward from a location immediately below the opened tube 5 for insertion thereof into the tube 5 does not permit accurate insertion, unless the tube 5 is held open substantially wider relative to the external size of the object 8. Moreover, as a matter of reality, the tube 5 as spread and opened by and between the belts 2, 2a can hardly be in round open condition and is usually opened in somewhat flatly deformed fashion. Where the diameter of the tube 5 is not so much different from the outer diameter of the object 8, therefore, the tube 5 and the object 8 may interfere with each other at the moment of the object 8 being inserted into the tube 5, which poses a problem in terms of insertion accuracy.